1. Technical Field of the Invention
The present invention relates to communication switches and, more particularly, to an ethernet switch architecture.
2. Description of Related Art
Ethernet is the most popular physical layer LAN technology in use today. Ethernet is popular because it strikes a good balance between speed, cost and ease of installation. These benefits, combined with wide acceptance in the computer marketplace and the ability to support virtually all popular network protocols, make Ethernet an ideal networking technology. The Institute for Electrical and Electronic Engineers (IEEE) defines the Ethernet standard as IEEE Standard 802. This standard defines rules for configuring an Ethernet network as well as specifying how elements in an Ethernet network interact with one another.
In a communications device, such as a network switch, data units are received on ports which are typically coupled to a switch matrix, otherwise referred to as a crossconnect or crossbar. The received data units are forwarded from the respective ports of the crossbar switch to one or more other ports coupled to the crossbar switch. In a typical network switch, the ports are disposed on printed circuit boards or chips and the crossbar switch is likewise disposed on a chip.
A crossbar switch has the characteristics of being able to effectively couple an input data stream appearing at any specified one of the crossbar switch ports to one or more crossbar switch output ports.
As communication systems evolve toward using embedded switches as a backbone, it becomes necessary to be able to extend the connectivity to this backbone. One approach is to aggregate lower level ethernet links into higher level aggregation switches. Within a telecom system, rack space is at a cost premium. Therefore, it is beneficial from a cost, power, and management perspective to provide a maximum number of ports into the minimum rack space. Generally, single unit ethernet switches offer a total of 12 ports which limits the number of ethernet links (additional racks) that can be aggregated. Thus, the number of expansion racks in a Soft-Switch, for example, are limited by the availability of only 12 ports.
A commonly used crossbar chip is the GT-48304 12 port crossbar by Galileo Technologies, a Marvell Company. As interconnects are increased, the design complexity inhibits the manufacture of crossbar chips with more port availability, thus, larger and more expensive solutions (e.g. a multi-card chassis) are used to increase port density. Therefore, there exists a need for a novel architecture for increasing port availability with more acceptable cost, power and space requirements.